A note on spherical structures in chars from vitrinites of coking rank

1977 ◽  
Vol 109 (1) ◽  
pp. 159-163 ◽  
Author(s):  
F. Goodarzi ◽  
D. G. Murchison
Keyword(s):  
Spherical Structures

Video real-time imaging of artificial membranes during freeze-drying by cryo-electron microscopy

1988 ◽  
Vol 46 ◽  
pp. 16-17
Author(s):  
Alan S. Rudolph ◽  
Ronald R. Price
Keyword(s):  
Real Time ◽  
Self Assembly ◽  
Freeze Drying ◽  
Video Capture ◽  
Drying Process ◽  
Artificial Membranes ◽  
The Past ◽  
Cryo Electron Microscopy ◽  
Spherical Structures ◽  
Capture Techniques

We have employed cryoelectron microscopy to visualize events that occur during the freeze-drying of artificial membranes by employing real time video capture techniques. Artificial membranes or liposomes which are spherical structures within internal aqueous space are stabilized by water which provides the driving force for spontaneous self-assembly of these structures. Previous assays of damage to these structures which are induced by freeze drying reveal that the two principal deleterious events that occur are 1) fusion of liposomes and 2) leakage of contents trapped within the liposome [1]. In the past the only way to access these events was to examine the liposomes following the dehydration event. This technique allows the event to be monitored in real time as the liposomes destabilize and as water is sublimed at cryo temperatures in the vacuum of the microscope. The method by which liposomes are compromised by freeze-drying are largely unknown. This technique has shown that cryo-protectants such as glycerol and carbohydrates are able to maintain liposomal structure throughout the drying process.

Nanoemulsions Loaded with Amphotericin B: Development, Characterization and Leishmanicidal Activity

2019 ◽  
Vol 25 (14) ◽  
pp. 1616-1622 ◽  
Author(s):  
Gabriela Muniz Félix Araújo ◽  
Gabriela Muniz Félix Araújo ◽  
Alana Rafaela Albuquerque Barros ◽  
Alana Rafaela Albuquerque Barros ◽  
João Augusto Oshiro-Junior ◽  
...  
Keyword(s):  
Amphotericin B ◽  
Average Diameter ◽  
Isopropyl Myristate ◽  
Neglected Diseases ◽  
Clinical Form ◽  
Hydrophobic Compounds ◽  
Internal Phase ◽  
Oil In Water ◽  
Spherical Structures ◽  
Lipid Formulations

Leishmaniasis is one of the most neglected diseases in the world. Its most severe clinical form, called visceral, if left untreated, can be fatal. Conventional therapy is based on the use of pentavalent antimonials and includes amphotericin B (AmB) as a second-choice drug. The micellar formulation of AmB, although effective, is associated with acute and chronic toxicity. Commercially-available lipid formulations emerged to overcome such drawbacks, but their high cost limits their widespread use. Drug delivery systems such as nanoemulsions (NE) have proven ability to solubilize hydrophobic compounds, improve absorption and bioavailability, increase efficacy and reduce toxicity of encapsulated drugs. NE become even more attractive because they are inexpensive and easy to prepare. The aim of this work was to incorporate AmB in NE prepared by sonicating a mixture of surfactants, Kolliphor® HS15 (KHS15) and Brij® 52, and an oil, isopropyl myristate. NE exhibited neutral pH, conductivity values consistent with oil in water systems, spherical structures with negative Zeta potential value, monomodal size distribution and average diameter of drug-containing droplets ranging from 33 to 132 nm. AmB did not modify the thermal behavior of the system, likely due to its dispersion in the internal phase. Statistically similar antileishmanial activity of AmB-loaded NE to that of AmB micellar formulation suggests further exploring them in terms of toxicity and effectiveness against amastigotes, with the aim of offering an alternative to treat visceral leishmaniasis.

Solid and Hollow Micro and Nano Spherical Structures: in Polysilicon and Phosphosilicate Glass

1994 ◽  
Vol 372 ◽  
Author(s):  
M. M. Farooqui ◽  
A. G. R. Evans
Keyword(s):  
Ion Beam ◽  
Three Dimensional ◽  
Optical Components ◽  
Circular Symmetry ◽  
Spherical Structures ◽  
Phosphosilicate Glass ◽  
Micro Systems ◽  
Micro Structures ◽  
Microfabrication Techniques

Fabrication of three dimensional micro structures in silicon and silicon related materials is becoming increasingly important for the realisation of micro systems comprising of sensors, actuators, transducers and analytical assemblies. Fabrication of such devices so far has been mostly in form of structures defined by the crystal planes of silicon, or has involved sophisticated technologies such as ion beam machining, replication using LIGA, or micromachining techniques involving a sequence of alignment and etch stages using binary masks. Structures with circular symmetry are of great interest as micro optical components amongst others, and these are not easily amenable to microfabrication techniques commonly employed.

Imaging of small spherical structures in CT: simulation study using measured point spread function

2007 ◽  
Vol 46 (3) ◽  
pp. 273-282 ◽  
Author(s):  
Masaki Ohkubo ◽  
Shinichi Wada ◽  
Masayuki Kunii ◽  
Toru Matsumoto ◽  
Kanae Nishizawa
Keyword(s):  
Simulation Study ◽  
Point Spread Function ◽  
Point Spread ◽  
Spread Function ◽  
Ct Simulation ◽  
Spherical Structures

Field Transforms for Multilayered Cylindrical and Spherical Structures of Finite Conductivity

1975 ◽  
Vol 53 (11) ◽  
pp. 1078-1087 ◽  
Author(s):  
E. Bahar
Keyword(s):  
Radius Of Curvature ◽  
Finite Conductivity ◽  
Electromagnetic Propagation ◽  
Wave Guides ◽  
Spherical Structures ◽  
Fourier Type ◽  
The Relationship ◽  
Conducting Cylinders ◽  
Dielectric Structures ◽  
Watson Transform

Problems of propagation around multilayered cylindrical or spherical structures possessing highly conducting cores have been analyzed in terms of discrete sets of modes. However, when propagation through the core of the structure is significant and of particular interest, the discrete set of modes is not suitable for the complete expansion of the electromagnetic fields.To provide a suitable basis for the expansion of the electromagnetic field in nonuniform multilayered, cylindrical or spheroidal, dielectric structures we derive expressions for the electric and magnetic field transforms consisting of both a discrete and a continuous spectrum of waves. The relationship between these transforms, the Kontorowich–Lebedev transform, and the discrete Watson transform is discussed. When the radius of curvature of the structure is infinite these transforms merge with generalized Fourier type transforms.The transforms can be used to investigate electromagnetic propagation through irregularly shaped dielectric wave guides, and through irregularly shaped spheroids. It can also be used to solve the problem of propagation in the interior (concave side) of irregularly shaped conducting cylinders or spheroids.

scholarly journals Laboratory evolution of virus-like nucleocapsids from nonviral protein cages

2018 ◽  
Vol 115 (21) ◽  
pp. 5432-5437 ◽  
Author(s):  
Naohiro Terasaka ◽  
Yusuke Azuma ◽  
Donald Hilvert
Keyword(s):  
Aquifex Aeolicus ◽  
Cellular Functions ◽  
Laboratory Evolution ◽  
Virion Assembly ◽  
Protein Cages ◽  
Protein Cage ◽  
Spherical Structures ◽  
Rna Genome ◽  
Biological Environment

Viruses are remarkable nanomachines that efficiently hijack cellular functions to replicate and self-assemble their components within a complex biological environment. As all steps of the viral life cycle depend on formation of a protective proteinaceous shell that packages the DNA or RNA genome, bottom-up construction of virus-like nucleocapsids from nonviral materials could provide valuable insights into virion assembly and evolution. Such constructs could also serve as safe alternatives to natural viruses for diverse nano- and biotechnological applications. Here we show that artificial virus-like nucleocapsids can be generated—rapidly and surprisingly easily—by engineering and laboratory evolution of a nonviral protein cage formed by Aquifex aeolicus lumazine synthase (AaLS) and its encoding mRNA. Cationic peptides were appended to the engineered capsid proteins to enable specific recognition of packaging signals on cognate mRNAs, and subsequent evolutionary optimization afforded nucleocapsids with expanded spherical structures that encapsulate their own full-length RNA genome in vivo and protect the cargo molecules from nucleases. These findings provide strong experimental support for the hypothesis that subcellular protein-bounded compartments may have facilitated the emergence of ancient viruses.

The role of weak interactions in the crystal packing of two novel 1D Hg(II) coordination polymers and investigation for preparation of their rod and spherical structures

2020 ◽  
Vol 501 ◽  
pp. 119243 ◽  
Author(s):  
Ghodrat Mahmoudi ◽  
Payam Hayati ◽  
Khosro Mohammadi ◽  
Ardavan Masoudiasl ◽  
Joel T. Mague ◽  
...  
Keyword(s):  
Coordination Polymers ◽  
Crystal Packing ◽  
Weak Interactions ◽  
Spherical Structures

scholarly journals Molecular Characterization of Arabinoxylan from Wheat Beer, Beer Foam and Defoamed Beer

Molecules ◽  
2019 ◽  
Vol 24 (7) ◽  
pp. 1230
Author(s):  
Jie Li ◽  
Jinhua Du
Keyword(s):  
Molecular Weight ◽  
Molecular Characterization ◽  
Average Molecular Weight ◽  
Monosaccharide Composition ◽  
Weight Average Molecular Weight ◽  
Substitution Degree ◽  
Significant Difference ◽  
Spherical Structures ◽  
Beer Foam

This research was to explore the distribution and some molecular characterization of arabinoxylan in wheat beer (B), beer foam (BF) and defoamed beer (DB) because of the crucial influences of arabinoxylan on wheat beer and its foam. The purified arabinoxylan from B, BF, and DB were fractionated by ethanol of 50%, 67%, 75%, and 80%. The monosaccharide composition, substitution degree (Ara/Xyl ratio, A/X), and average degrees of polymerization (avDP) of arabinoxylan were investigated. Molecular weight and microstructure were also involved in this study by GPC-LLS and SEM, respectively. Under the same ethanol concentration, the arabinoxylan content in the BF was higher than the other two, respectively, and it was precipitated in BF fraction with 50% ethanol which accounted for 80.84% of the total polysaccharides. Meanwhile, the greatest substitution degree (A/X) and highest value of avDP of the arabinoxylan was found in all beer foam fractions regardless of the concentration of ethanol used. The average degrees of polymerization (avDP) of arabinoxylan displayed a significant difference (p < 0.05) among B, BF, and DB. Furthermore, arabinoxylan presented varied microstructure with irregular lamellas and spherical structures and the weight-average molecular weight (Mw) of arabinoxylan showed the lowest values in BF, while the largest values were shown in DB. Therefore, arabinoxylan was more accumulated in beer foam, especially in 50% ethanol, characterised by greater value of A/X and avDP, as well as lower Mw. It was suggested that the arabinoxylan played important roles in maintaining wheat beer foam characteristics.

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